Reduced Salt Benefits Pre-Hypertensive Hearts

/Home/Complications of Diabetes/Diabetes and Hypertension/Diabetic Hypertension Prevention

Reduced Salt Benefits Pre-Hypertensive Hearts
DOC News September 1, 2007
Volume 4 Number 9 p. 7

Knowing sources of dietary sodium makes cutting intake easier
Joene Hendry

Lowering sodium intake over the long term appears to yield more than just blood pressure benefits. A recent follow-up of the two Trials of Hypertension Prevention studies (TOHP I and TOHP II) identifies a 25% lower risk of cardiovascular outcomes among participants assigned to a sodium reduction intervention.

Most notably, the reduction in cardiovascular disease risk occurred among pre-hypertensive individuals—those with diastolic blood pressure of 80–89 mmHg who were not taking anti-hypertensive medications, says co-author Nancy R. Cook, ScD, of Brigham and Women's Hospital and Harvard Medical School in Boston. Researchers identified the risk reduction 10–15 years after completion of the trials.1

Co-author Jeffrey A. Cutler, of the National Heart, Lung, and Blood Institute, describes these findings as "unique and confirmatory."

They're "unique in being the first results for cardiovascular outcomes from long-term follow-up of a randomized clinical trial of sodium reduction in humans," Cutler says. They're confirmatory in demonstrating substantial long-term benefits of sodium reduction, he adds.

The results also reinforce current nutritional guidelines, based on the solidly established relationship among higher sodium intake, higher blood pressure, and a greater risk of developing hypertension, Cutler notes.

The message here is that most people are not immune from the effects of high dietary sodium, says American Dietetic Association (ADietA) spokesperson Christine Gerbstadt, MD, RD.


Salt Inside Your Lunchbox
Sodium content of a sample lunch: soup, crackers, salad:
* A 19-oz can of Progresso Traditional Homestyle Chicken soup contains 800 mg sodium per serving (30% daily value of sodium per serving). But the can contains "about two servings," so eating the entire can provides nearly 1,600 mg sodium.
* One serving of Keebler Club crackers (4 crackers) contains 150 mg sodium; 8 crackers = 300 mg sodium.
* A salad with 2 tbsp dressing provides 110–500 mg sodium.3

Approximate total: 1,060–2,400 mg sodium.

But here's the rub: TOHP participants did more than simply hide the salt shaker. They underwent individual and group interventions to reduce dietary sodium intake in all their food choices.

SODIUM CONSUMPTION VERSUS NEED
The estimated average sodium intake in the U.S. is 3,375 mg/day, with males consuming more than females in all age groups (see chart).2

The U.S. Department of Agriculture's (USDA's) 2005 Dietary Guidelines for Americans recommend that most people consume <2,300 mg/day of sodium—the equivalent of about 1 tsp of salt, or "a reduction of about a third from actual consumption," Cook says.3

Yet, an average healthy person can consume substantially less sodium, closer to 1,500 mg/day without health consequences, says ADietA spokesperson Suzanne Farrell, MS, RD. In fact, this is the daily recommended sodium intake for middle-aged and older individuals, African Americans, and those with hypertension.3 "Only high-endurance athletes would require more sodium," Farrell notes.

SODIUM-REDUCTION TIPS
Only 11% of the average American's sodium intake comes from a salt shaker—5% during cooking and 6% at the table. Lowering sodium intake is difficult because 77% of dietary sodium comes from processed foods. The remaining 12% already exists in whole, unprocessed foods.3

Farrell, who counsels mostly physician-referred patients on weight management, diabetes, and hypertension, advises physicians to alert patients to the following sodium-reduction techniques:

* Heed the sodium content listed in nutrition fact boxes on food labels. Any listing of &#8805;20% is a high-sodium food. A low-sodium food contains &#8804;5% per serving. Purchasing foods labeled "low" or "reduced" sodium is good practice, but a "reduced sodium" claim indicates only a 25% reduction of sodium compared with the corresponding regular product. Obvious high-sodium sources are salted, cured, and salt-preserved foods such as pickles, olives, lunch meats, ham, canned vegetables, canned soups, and salted snacks, chips, and crackers, Gerbstadt says. But sauces, gravies, salad dressings, prepared mixes (even for sweet foods, like cakes), cheeses, butter, and margarine also contain salt.
* When eating out, watch for red-flag words like smoked, au jus, soy sauce, broth, pickled, cured, or corned. Limit condiment intake since ketchup, soy or teriyaki sauce, and mustard contain substantial amounts of sodium. Order salad dressings and sauces on the side to minimize sodium intake. A dip of the empty fork, rather than a forkful of food, into the sauce or dressing also can help reduce salt intake. "It's pretty remarkable how much less sauce or dressing one consumes using this method," Farrell notes.
* Increase fiber intake and eat nine daily servings of vegetables and fruits. The latter is the easiest way to reduce sodium intake, Gerbstadt notes. Another good tip is to rinse the liquid from canned beans or vegetables. "You lose much of the sodium and very little in vitamins," she says.
* Understand why monitoring sodium intake is important and what level of sodium to consume daily. "A registered dietitian is the person best able to help patients learn how to achieve their goals," Gerbstadt says.

Ultimately, says Cook, the food industry stands to make the biggest impact on reducing dietary sodium. Both she and Cutler advocate for reduced-sodium content in processed and restaurant foods, which Cutler says "is likely to be a key strategy for reducing the adverse effects of high salt intake on cardiovascular health." {blacksquare}


Footnotes
FYI
The American Dietetic Association (ADietA) brochure on salt is available at www.eatright.org/ada/files/Mrs_Dash.pdf.

A more general ADietA brochure on food labels can be found at www.eatright.org/ada/files/Get_Smart.pdf.

The USDA's Dietary Guidelines for Americans 2005 are available online at www.healthierus.gov/dietaryguidelines/.

References

1. Cook NR, Cutler JA, Obarzanek E, et al.: Long term effects of dietary sodium reduction on cardiovascular disease outcomes: Observational follow-up of the trials of hypertension prevention (TOHP). BMJ 334:885, 2007.[Abstract/Free Full Text]

2. Centers for Disease Control and Prevention: National Health and Nutrition Examination Survey: Intake of calories and selected nutrients for the United States population, 1999–2000. Available online at www.cdc.gov/nchs/data/nhanes/databriefs/calories.pdf. Accessed May 15, 2007.

3. U.S. Department of Agriculture: Dietary Guidelines for Americans 2005. Available online at www.health.gov/dietaryguidelines/dga2005/document/html/chapter8.htm. Accessed May 15, 2007.

© 2007 American Diabetes Association